IMO the question that needs to be answered is who is going to show up to the games.
If they are all going to be there all the time 11 or 12 is fine, if they are not you need a large enough Roster were you are not running around looking for quest players.
14-16 is a good number if you have team players rather than girls/parents who think it's all about them.
Thanks everyone. That jibes with my thinking. We've had a smaller core at 18U in the past (that we knew well) as we continued this fall with a newer group (a few holdovers) and we had a lot of misses and not as much competition as I'd like. I haven't managed a 15-player roster before, I know all the tricks but just haven't managed the people (player/parent) dynamics yet. My thought: practice hard and often, play a tough schedule, let the cream rise while respecting and helping each and every player best we can. And be ready for a few malcontents (something we haven't faced with smaller rosters)....TKS